Alastair Cook has admitted that England may be forced to go into the opening performance of their Ashes defence in Brisbane in a fortnight without a full dress rehearsal.

Cook was one of the players who benefited most from England's carefully-planned preparations for the last Ashes series in Australia three years ago, building sufficient form and confidence as one of the top seven who played in each of the three warm-up games to score 67 and his famous unbeaten 235 in the first Test at the Gabba.

But after missing the low-key opening game of this tour in Perth with a mild recurrence of his long-term back complaint, the captain concedes that England are having to be much more flexible three years on.

"It's very different to 2010-11," he said. "We came here very clear what our full strength side was and on that tour we played the first two warm-up games as that Test match XI.

"In this situation circumstances are different. We are unsure of pretty much two places and it's exciting because everyone in the squad knows that and watching that competition grow, if someone grabs that opportunity he is going to find himself in a good place."

Cook believes that the greater experience of Australian conditions in this squad makes a repeat of those 2010-11 preparations unnecessary. "The bowlers are more experienced in these conditions than last time we were here," he added. "Jimmy Anderson, Stuart Broad and Graeme Swann know their games and conditions they are about to bowl in so it is a matter of tailoring to their needs."

Cook explained that Broad had preferred to miss the opener in Perth if it allowed him to prepare for Brisbane with consecutive fixtures against Australia A in Hobart and then the final warm-up game against a New South Wales Invitational XI in Sydney next week.

But he made it clear that England have arrived with no hard and fast plans for their batting order. "We are open to all possibilities," he said when asked whether there was a chance of Michael Carberry coming in to open and Joe Root dropping down the order – as the team's least favourite media pundit Shane Warne has helpfully suggested. "We haven't decided on our batting line-up."

Perhaps worryingly for Root, Cook stressed the importance of rectifying the problems England had against the new ball in the home Ashes series, when they were three down for 64 or fewer in five of their first eight innings – although the captain would be the first to acknowledge his own share of the responsibility for the regular loss of early wickets in an unusually lean run, averaging less than 30 for the series.

"Especially with the Kookaburra ball it's a situation we can't allow to happen again," he said. "Sometimes in England with overhead conditions that does happen. In Australia the bigger scores do happen and we know that is an area of major improvement we need coming into the series."

Cook and England are thought to be ready to accept Hot Spot as part of the decision review system for the series, after Channel Nine reversed their original decision to scrap the thermal imaging technology following all the controversy that surrounded it earlier in the year. However the possibility that Real Time Snickometer, a new gadget developed by the same company, could be used for the first time in the Ashes series is fading by the day, with the International Cricket Council considered highly unlikely to conduct such a high-profile trial.

The ICC are due to confirm the match officials for the series early next week, with every likelihood that they will come from the same group of four as officiated in the summer – the only members of the elite umpiring panel not from either England or Australia.